HfO2 gate insulator formed by atomic layer deposition for thin-film-transistors

We have investigated the effects of annealing temperature on the physical and electrical properties of the HfO2 film deposited by an atomic layer deposition (ALD) method for high-k gate oxides in thin-film-transistors (TFTs). The ALD deposition of HfO2 directly on the Si substrate at 300 °C results in the formation of thin HfSixOy interfacial layer between Si and HfO2. The subsequent low temperature N2-annealing of HfO2 films (i.e., 300 °C) using a rapid thermal processor (RTP) improves the overall electrical characteristics of HfSixOy–HfO2 films. Based on the current work, we suggest that HfO2 film deposited by the ALD method is suitable for high-k gate oxides in TFTs, which have to be fabricated at low temperature.